Endoscopic surgery is performed within the natural cavities of the human body. A small hole is created in the skin of the patient and an optical instrument, the endoscope, is positioned in the cavity. The endoscope can consist of a rigid flexible tube having channels for light, fluid, gas etc depending on the endoscopy application. Specific applications of this procedure include: Transurethral resection (TUR), Laparascopy, enteroscopy, colonoscopy, sigmoidoscopy, proctoscopy, cytoscopy, arthoscopy, etc.
In the urology application, or transurethral resection (TUR), this technique is used in surgery of body cavities like prostate, bladder, urethra or kindly etc. Further in this patent application, the surgical site for an endoscopic procedure in general, will be referred to as the body cavity.
During endoscopic procedures the body cavity is not opened, instead the surgical area is made visible through a lens-device, an endoscope. To obtain a visible operation site the body cavity is pressurised with irrigation liquid or with gas. In the endoscopic procedures where liquid is used, normally TUR-, arthroscopy- and hysteroscopy procedures, the irrigation flushes the operation site and is some cases also put an over pressure in the site to extend it. Irrigation in these cases is performed through gravity or by means of a pump device. In the endoscopic procedures where gas is used it is always insufflated through a pump system.
The above-mentioned pump devices are further in this patent application referred to as an insufflator, an irrigation pump or just the pump.
The pump is used to irrigate or flush the body cavity with fluids or gas. The insufflator pump uses Carbone dioxide (CO2) as a rule, and the pump is usually an insufflation type pump, moving the gas from a gas container to the body cavity via a tube. The irrigation pump transports the fluids from a bag or container via a tube into the body cavity. Normally uses a sterile solution like saline or glycine and the pump is usually a peristaltic roller type pump. The pressure is set manually by practise in both pump types. It may be higher for certain body cavities, but setting of the pressure can also be done arbitrarily.
Existing liquid and gas management systems are either operated by a fixed flushing volume (i.e. Volumetric devices) programmed by the operator of the system when starting the procedure (normally an ml/min value), or by a fixed pressure target for the system. The operator of the system upon start of the process selects the target pressure. Existing pressure controlled systems have different ways of measuring the pressure, but the overall technique is indirectly measurement of the pressure on the irrigation side of the system, i.e. the delivery side.
A gas management system is most often used during Laparoscopy but have some safety limitation in this area. During the procedure 100% Carbone dioxide is pumped into the body cavity, i.e. intra-peritoneal. Carbone dioxide is potentially dangerous in relatively small concentrations for the human body and a leakage from the operating site into other body cavities like the lung can cause fetal outcomes. Another safety aspect of this technique is the over pressure that is built up in the body cavity by the inflated gas. Too high pressure will have a negative effect on circulation in- and around the body cavity. As several systemic vessels pass the Laparoscopic body cavity, a reduction of the circulation in- and around the body cavity can have a dramatic effect on the overall circulation of the body.
When a fluid management system is used the limitation with the volumetric system is that an excessive liquid volume is needed to achieve a rinsing effect. The limitations with the fixed pressure target systems are firstly that it is impossible to flexibly change the pressure depending on the needs during the operation. Thereby an unnecessary high pressure is used in many cases resulting in tissue swelling and subsequently a risk of tissue damage. Secondly the fixed pressure controlled systems seldom operate at the fixed pressure target as the systems are based on the measurement of an indirect pressure in the operation site. When the operation site is drained from liquid it takes some time for such a system to react to a lower pressure due to volume/pressure hysteresis of the tissue, and the reaction time can sometimes be very long resulting in an unnecessarily long time of bad visibility during the endoscopic procedure.
Recently, the inventor herein have developed a novel indirect method, disclosed in US patent publication 20070249993 for irrigation of body cavities under the independent control of pressure and flow through the cavities and depending mainly on the detection of blood cells, red blood cells, haemoglobin and/or debris from the surgical site. The novel methods and devices allow for the detection of the pressure in the body cavity without the introduction of instrumentation for pressure measurement. In the invention the control over the pressure in, and flow through, the surgical site, is achieved by the use of signals from optical sensors provided at a tubing on the outflow site of the body cavity wherein the sensors detect blood cells, red blood cells, haemoglobin and/or debris in the liquid coming out from the surgical site and send signals to a control unit which via a second control unit adjust the inflow liquid pump and/or the outflow liquid device to keep a constant pressure at all times.
With all the aforementioned methods the body cavity expands as a result of the pressure from irrigation or insufflation. Consequently, the higher the body cavity is pressurised, the more distension is accomplished, and subsequently a better view is gained to the surgeon. The drawback is the risk involved with too high pressure settings. If the pressure in the body cavity built up by inflated gas or by irrigated fluids, reach a higher pressure then in the surrounding tissue, vessels or organs potentially tissue damage can occur, with several side effects, which are further discussed below.
Moreover, during the surgical procedure, tissue is surgically treated. For example electro-surgical devices, scissors, tweezers or power tools are used. This normally results in emissions of particles in the operating area such as free tissue, blood cells, boon pieces etc. Emerging free particles obstructs visibility, and it is of course in general desirable to stop distribution of such particulates and moreover to stop bleeding during surgery.
The pressure controlled system according to the known art gives a pressure that has been set by the operator. It will mostly be too high as the operator sets the peek pressure that will be required during the procedure. In the volumetric system the delivered pressure and thereby the pressure in the operating site is unknown. In the pump systems based on US patent publication 20070249993 a better pressure controlled is achieved but the pressure setting is independent on actual pressure in the cavity and it can therefore be adjusted by the system to unnecessary high levels compared to actual needs.
In general the blood flows from the heart by the arterial system to smaller vessels, arterioles, and further into the capillary system. The pressure drops along this liquid pathway. If a vessel in, or in the immediate proximity of the body cavity is broken, the blood will leave the vessel at the point of rupture if the blood pressure in the damaged vessel is higher than in the body cavity, i.e. perfusion pressure is higher than body cavity pressure. The broken vessel would close if the pressure in the body cavity is increased above the perfusion pressure in the vessel, i.e. if the irrigation- or the insufflation pump makes the pressure in the body cavity higher than that of the broken vessel tip. Thus, a properly selected pump pressure, based on the actual perfusion pressure, would hold back the blood from the damaged vessels without over pressurize the operating site. Using this strategy for pressurizing the irrigated saline will also avoid problems with inflow of irrigated saline into the blood stream via the broken vessels. This will lead to a dilution of the blood resulting un-clinical values of several life supporting substances in the blood. This situation is occurring mostly during TUR surgery and has been named TUR Syndrome.
Moreover, in surgeries where the visibility is dependent on flushing of the body cavity with liquid, like TUR, arthroscopy and hysteroscopy, the irrigation pumps also shall maintain an appropriate flow, for rinsing purposes, in combination with the properly selected pressure.
From the visibility point of view and from these last arguments it is concluded that the irrigation pressure and flow through the body cavity delivered by the pump should be as high as possible but should not reach physical dangerous levels.
Nevertheless, in those cases when the pump pressure is too high, tissue damage is likely to occur as a result of that the irrigated liquid or gas goes into other compartments outside the body cavity, into blood vessels and/or into organs. This would put the patient at risk resulting in sever side-effects and lead to death.
A precise control of pressure in the body cavity is therefore of vital importance. It is beneficial to keep the irrigation pressure as low as possible for minimised risk, but as high as possible for best surgical conditions.
Several patent references disclose different approaches to overcome the aforementioned drawbacks and optimize the pressure in the body cavity. Various systems have been proposed in which a combination of endogenous/physiological parameters is used to control a variety of infusion systems.
U.S. Pat. No. 7,510,542, teaches a dual pump irrigation/aspiration pump system capable of operating in a plurality of different modes suitable for a variety of different endoscopic surgical procedures. The system calculates the pressure and adjusts flow to maintain surgeon requested pressure levels at the surgical site while controlling outflow. In a preferred embodiment a pressure control system provides inferred pressure information representative of the pressure at the work site.
US publications 20050126961, and U.S. Pat. No. 6,780,322 disclose a multipurpose hemofiltration system and method for continuously monitoring the flow rates of drained fluid, blood and infusate. A supervisory controller can monitor patient parameters, such as heart rate and blood pressure, and adjust the pumping rates (pump speed) accordingly. The purpose is to provide a linear response or a non-linear (curvilinear) response to the observed changes in the selected monitored parameters.
US 20070055198 refers to a blood volume control method including monitoring a condition of a patient such as hematocrit and automatically adjusting the infusion to maintain the monitored condition at a predetermined value. There are Hct sensors connected to the patients, wherein the sensor generates a control signal for the infusion pump.
US 20080183287 discloses a demand responsive physiological control system for use with a rotatory blood pump; said system including a pump controller which is capable of controlling pump speed of said pump; said system further including a physiological controller, and wherein said physiological controller is adapted to analyze input data relating to physiological condition of the user e.g pulsatile flow, heart rate, and wherein said physiological controller sends a speed control signal to said pump controller to adjust pump speed.
U.S. Pat. No. 5,503,624, relates to an infusion system having a control device for automatically adapting the dosage of drugs to the multi-factorial influences of the patient's condition which can change over time. The system is particularly used for stabilizing the blood pressure during extracorporeal purification of the blood in patients. It is provided with a control device considering a plurality of influence values e.g. plasma volume, hematocrit, pulse, cardiac output per minute and electrolyte concentrations,
US 20090069743, Refers to an integrated sensor system for use with an infusion system and include at least one sensor disposed within a catheter. The sensor system may include a sample cell that is in fluid communication with the infusion system, which sample cell may be used with an analyzer to determine a patient's condition. The sensor system may be integrated within a control system for real time monitoring of patient parameters for pump control e.g. via patient fluid analysis.
US 20080262418, teaches an automated therapy system having an infusion catheter, a sensor adapted to sense a patient parameter, and a controller communicating with the sensor and programmed to control flow output from the infusion catheter into a patient based on the patient parameter without removing fluid from the patient. The sensor comprises a blood pressure sensor and the patient parameter is blood pressure. The aim is to control infusion of fluid into patient in order to optimize the therapy being provided. In an embodiment the inventors mention that irrigation and/or lavage of bodily tissues cavities or spaces (or other patient interventions) may be optimized by using a sensors to report pressure or other parameters surrounding the access device in order to automate and optimize the irrigation/lavage.
U.S. Pat. No. 5,800,383, discloses a fluid management system for irrigation of a body cavity and in particular for use in arthroscopic surgery having a pressurized fluid circuit for supplying irrigation fluid and a vacuum fluid circuit for withdrawing waste fluid from the cavity. Some of the features include the monitoring and tracking of cavity pressure and flow rates to predetermined pressure and flow rates, tracking cavity to mean blood pressure, overpressure protection, a plurality of pressure and flow rate baseline settings, monitoring, setting and controlling saline supply, and specialized functions for providing pressure and flow rates for typical surgical procedures such as lavage, clear view, and burr/shaver. The invention discloses means for setting desired cavity pressure manually or automatically in relationship to the patient's blood pressure.
Accordingly, there is a need for a system that deliver fluids or gas during the above-specified endoscopic procedures with as high pressure as needed for the individual patient in a dynamic fashion, thereby avoiding damaging levels but a system that quickly adjust to actual needs during surgery.
Thus, it would from a pressure setting point of view be advantageous to have a system that control the patient's actual perfusion pressure in the body cavity area and adjust delivered irrigation and inflated gas pressure based the patient's individual need.
The present invention satisfies this need and provides related advantages as well.